On my 402-160 mold, I found that adding about 1% tin to my 50/50 COWW/SOWW alloy and then running at about 720* will give me excellent results with a reject rate well below 10%. The mold does like to run hot, generally bordering on frosting the boolits. The 359640 is showing signs it likes things the same as the 402-160. Both molds are 2-cav but I have just started to cast with the 359640. There is a little bit of a learning curve with each mold but once you get them running they don't want to stop.